<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <script type="text/javascript" src="test.js"></script>
    <script type="text/javascript">


    </script>
    <style>
        .main{
           border:1px solid red;
            overflow: hidden;
        }
        .div1 {
            float: right;
            width: 200px;
            height: 200px;
            background: #75356b;
        }

        .div2 {
            float: right;
            width: 200px;
            height: 300px;
            background: #15e4ff;
        }

        .div3 {
            position: relative;
            top: 150px;
            z-index: -1;
            width: 100%;
            height: 1px;
            background: #000000;
        }
    </style>
</head>
<body>
<div class="main">
    <div class="div1">

    </div>
    <div class="div2">

    </div>
    <div class="div3">

    </div>
</div>
</body>
</html>